Telescoping gamma match antenna construction



J. D. GUEST March 21, 1961 TELESCOPING GAMMA MATCH ANTENNA CONSTRUCTIONFiled Jan. 15, 1958 3 Sheets-Sheet 1 James 0. G 95 INVENTOR.

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J. D. GUEST March 21, 1961 TELESCOPING GAMMA MATCH ANTENNA CONSTRUCTIONFiled Jan. 15, 1958 3 Sheets-Sheet 2 James 0. Guest 1N VENTOR.

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TELESCOPING GAMMA MATCH ANTENNA CONSTRUCTION Filed Jan. 15, 1958 3Sheets-Sheet 3 Fig.8

I06 502 Ax \g n Fi s James 0. Guest 1 N VE N TOR TELESCOPING GAMlVlAMATCH ANTENNA CONSTRUCTION James D. Guest, P.'0. Box 808, Duncan, Okla.

Filed Jan. 15, 1958, Ser. No. 709,036

Claims. (Cl. 343-722) This invention relates to an antenna constructionand more particularly to a beam-type antenna utilizing adjustable tuningmeans.

In beam-type antennas of the T match type or the Gamma match type, ithas often been found necessary 7 It is the principal object of thisinvention to provide a new type beam antenna incorporating variablecapacitor tuning wherein the capacitor is not subject to breakdown dueto normally occurring weather conditions.

It is a further object of this invention to provide an antenna which iseasier to manufacture andwhich is superior mechanically to thosepreviously used.

These together with other objects and advantages which will becomesubsequently apparent reside in the details of construction andoperation as more fully hereinafter described and claimed, referencebeing bad to the accompanying drawings forming a part hereof, whereinlike numerals refer to like parts throughout, and in which:

Figure 1 shows the invention in perspective illustrating the completeantenna construction;

Figure 2 shows the capacitive tuning element of the invention shown inFigure l in section;

Figure 3 shows a sectional view substantially through the plane 3-3 ofFigure 2;

Figure 4 shows a sectional view substantially through the plane 4-4 ofFigure 2;

Figure 5 shows a sectional view substantially through the plane 5-5 ofFigure 1;

Figure 6 illustrates another embodiment of the invention illustratinganother form of the capacitive tuning of Figure 2;

Figure 7 shows the variable capacitance used in multiple for multi-bandbeams;

Figure 8 is a sectional view substantially along the plane 88 of Figure6.

Numeral 10 generally designates the beam antenna apparatus wherein isillustrated generally a Gamma match type construction where numeral 12shows the driven element and 14 generally designates the variablecapacitor tuning portion. The invention more particularly lies inelement 14 which is shown in section in Figure 2 including threeconcentric electrically conductive portions of tubing members 16, 18 and20. Tube 20 is located within tube 16 and is held in place by an epoxyresin 22 having good electrical and adhesive characteristics. Of coursenumerous other adhesives could anass z Patented Mar. 21, 1961 be used inlieu of an epoxy resin. Tube 18 is in electrical contact with 16 andslidably surrounds it. A Lucite bushing 24 is secured in one end of tube18 and surrounds tube 20 in slidable relation thereto. A clamp 26 existson the outer portion of tube 18 to fixedly hold tube 18 in a particularposition in relation to tube 16. Tube 16 has a flat portion on one endthereof generally designated as 28 and is attached to the mountingassembly 31} by a hexagonal screw 32. A clamp 34 and strap 36 attachtube 20 to the driven element 12.

Figure 3 shows a sectional view substantially through the frame 3-3 ofFigure 2 wherein a clamp 26 may be seen held together at an extension 42by a hexagonal bolt 38 and cooperating nut 40. Within the clamp 26 aretubes. 18, 16, epoxy resin 22, and inner tube 20. Tube 18 contains slots44 which allow compression by clamp 26 to hold tube 18 in place withrespect to tube 16.

Figure 4 shows a sectional view through plane 4-4 of Figure 2 andillustrates the flat portion 28 of tube 16 held to the mounting assembly30 by hexagonal bolt 32 and cooperating nut 46.

Figure 5 shows the clamping means through plate 5-5 of Figure 1 whereinthe tuning element 14 is attached to the driven element 12.

In operation the tube 18 slides over tube 20 at point 48 and iselectrically insulated therefrom by Lucite bushing 24. Tube 18 iselectrically connected to tube 16 and slides over it at 50. The variablecapacitance of the arrangement consists of a fixed capacitive portionand an adjustable capacitive portion. The entire volume wherein isincluded the epoxy resin constitutes a fixed capacitive portion due tothe constant dimensions between tube 16 and tube'Ztl. The adjustablecapacitive portion is located between the end of the epoxy resin 52 andthe Lucite bushing 24. This adjustable capacitance is due to the varyingdimensions between tube 18 and tube 20 brought about when the tube 18 isslid over tube 16.

The tube 18 is slidably adjusted until a minimum standing wave ratio isobtained on the driven element. When the minimum standing wave ratio isobtained through adjustment of the location of the clamp 34, strap 36and clamp 54 along with the adjustment of slidable tube 18, all theclamps should then be tightened and the antenna is ready for use.

Figure 6 shows a further embodiment of the invention wherein only twotubes are utilized. Here tube is the outer tube and has a portion 28connected to a mounting assembly 30 in a manner identical with theembodiment shown in Figure 2. A suitable plastic insulation 102 existswithin outer tube 100 and encompasses inner tube 104. Screw means 106cooperate with insulation 102 and inner tube 104 to hold 104 in fixedrelation with respect to insulation 102 and outer tube 100. Theinsulation 102 is secured to the outer tube 100 but is slidably relatedto tube 104 as shown at 108.

Figure 8 shows a view substantially along the plane 88 of Figure 6showing members 100, 102 and 104 in concentric relationship.

This embodiment of the invention is similar in operation to theoperation of the device of Figure 2. Capacitive adjustment is made bysliding the tube 104 with respect to the insulation 102 whereby theeffective dimensions between the tube 100 and 104 are varied, therebyadjusting its capacitance. In order to achieve the minimum standing waveratio on the driven element clamp 34 along with strap 36 and clamp 54are moved and tube 104 is slidably adjusted in insulation 102 until aminimum standing wave ratio is obtained on the driven element.

Figure 7 shows the matching device to be used where one is feeding amulti-band beam. Three elements are 3 shown for tuning at threedifferent frequencies. In this view the coaxial line is shown feedingthe elements.

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed, and accordingly all suitable modifications and equivalentsmay be resorted to, falling within the scope of the invention asclaimed.

What is claimed as new is as follows:

1. An antenna construction including the combination of a driven membercomprising an elongated conductive rod and a tuning member comprising avariable capacitor including concentrically arranged telescopicallyrelated first and second elongated conductive tubes, and a tubularinsulator concentrically secured to one of said tubes and slidablyassociated with the other of said tubes, and conductive strap meansconnecting one of said tubes to said driven member.

2. An antenna construction including the combination of a driven membercomprising an elongated conductive rod and a tuning member comprising avariable capacitor including concentrically arranged telescopicallyrelated first and second elongated conductive tubes, and a tubularinsulator concentrically secured to one of said tubes and slidablyassociated with the other of said tubes, said first conductive tubesecured and electrically connected to an antenna mounting assembly saidsecond conductive tube extending beyond said first tube remote from saidmounting assembly, and conductive strap, means connecting said secondtube to said driven member, said strap, means, engaging said second tuberemote from said first; tube.

3. An antenna construction including the combination f. a d i n me ber qr s s n elongated duc i e rod and a, tuning member comprising a variablecapacitor including concentrically arranged telescopically related firstand second elongated conductive tubes, and a tubular insulatorconcentrically secured to one of said tubes and slidably associated withthe other of said tubes, said first conductive tube secured andelectrically connected to an antenna mounting assembly, said secondconductive tube extending beyond said first tube remote from saidmounting assqmbiy, and conductive strap means connect? tiveconcentrically related tubes, said tubes containingtelescopicallyrelated portions whereby the capacitance of the arrangement may bevvaried, one oi said conductive tubes containing a second conductive tubewithin, said second tube being held in place in relation to the firsttube by an adhesive filling the volume between the two tubes, saidsecond tube being longer than said first tube and extending beyond theconfines therefrom, a third tube disposed around said first tube inelectrical contact therewith and in slidable relation thereto and aninsulative ring slidably mounted around said second tube and secured tosaid third tube,

5. In an antenna construction, a variable capacitance arrangementcomprising a plurality of electrically conduc-' tive concentricallyrelated tubes, said tubes containing telescopically related portionswhereby the capacitance of the arrangement may be varied, one of saidconductive tubes containing a second conductive tube within, said secondtube being held in place in relation to the first tube by an adhesivefilling the volume between the two. tubes, said second tube being longerthan said first tube and extending beyond the confines therefrom, athird tube disposed around said first tube in electrical contact there--with and in slidable relation thereto and an insulative ring slidablymounted around said second tube, and secured to. third tube, a drivenmember, and conductive strap. means, electrically connecting said secondtube to said. driven member.

References Cited in the file of this patent UN TE T TES ATENTS 2,469,168Loughlin May'3, 1949 2,714,192 Pan et al. July 26, 1955 2,837,742 WeissJune 3, 1958- OTHER REFERENCES QST, August 1955, pp. 293l. QST, July1957, p. 30. QST, October 1957, pp. 19 and 20.

